Water and Solar

An interesting development regarding the use of solar PV technology to desalinate drinking water for cattle in the US recently came to my attention. 

©flickr/MartinPilat

There is obviously massive potential for technology that enables solar-powered water desalination, and there could be a huge market for this application, but so far high costs have prevented further development. The application of such technology to small-scale systems in off-grid areas, however, may be more viable - especially so when considering the falling cost of solar PV. In 2006, India’s Barefoot College built the country’s first solar-powered desalination plant in Kotri, a small village in the water-deprived region of Rajasthan. The village receives grid electricity, but this is erratic and insufficient to power an adequate supply of desalinated water for consumption and use in cooking and cleaning. The plant now provides a regular and affordable supply of drinking water for the entire rural community.

Khanna et al. (2008) write that solar distillation and desalination units in Rajasthan are “most appropriate for remote area dwellers because (they are) economical, easy to construct and maintain”. Their study determines that the use of solar energy for this purpose can help improve the health of rural people, is very cost-effective and requires greater investment by the government. They also point to ample solar radiation across the region as an important factor in their support. Arjunan et al. (2009) also consider the status of solar desalination in India and call for the wider use of solar distillation technology across the country. They argue for the attractiveness of solar distillation over other conventional technologies, pointing to its effectiveness as a small-scale solution for remote communities in rural areas where there is a lack of water. They do, however, point to the need for further research into improving efficiency. Bhattacharyya (2013) discusses how solar stills have improved in efficiency in recent years, and looks at the rising popularity of new ‘capillary’ forms of solar stills, a method of solar-powered water desalination that uses specialised material to facilitate rapid evaporation with minimal heating (Bhattacharyya, 2013). Bhattacharyya suggests that this type of solar still is an attractive method of accessing drinking water for rural people in remote areas. You can read a brief description of how the solar-powered distillation of water actually works here.

Children in Bolivia purifying water
using a solar water disinfection
method
©flickr/EcoagriculturePartners

In 2006 Kang et al. completed a study into a new commercial solar water heating system which was found to be cheap, easy to transport, effectively operational at scale and effective in preventing waterborne disease in both emergency situations and in small rural communities generally (Kang et al., 2006). Other solar-based water decontamination technologies that have spread over the world range from water disinfection via simple sun exposure to more complex hybrid solar water purification and PV conversion systems (McGuigan et al., 2012; Vivar et al., 2010).

Water scarcity is one of the biggest problems facing the world today. The application of solar power to decontaminating and desalinating water has been around for a while, but new technologies that are even more efficient and sustainable need to be invested in to ensure rural communities have access to a constant, continued supply of consumable water at both small and large scales in the future.